Biomedical subjects

J Adamski

Publications and source records attributed to J Adamski.

At least 19 recordsLinked to original sources

PubMed2006

Functional genome analysis indicates loss of 17beta-hydroxysteroid dehydrogenase type 2 enzyme in the zebrafish.

Among the family of 17beta-hydroxysteroid dehydrogenases, the type 2 (17beta-HSD 2) is the main enzyme responsible for inactivation of estrogens and androgens, catalyzing the oxidation of the C17 hydroxyl group. 17beta-HSD 2 has been studied only in mammals, its occurrence and function in other vertebrates hardly known. We investigated the presence of homologs in non-mammalian species and found sequences of 17beta-HSD 2 and its closest homolog 11beta-HSD 2 in zebrafish (Danio rerio), Takifugu rubripes, Tetraodon nigroviridis, Xenopus tropicalis and chicken databases. Furthermore, we cloned zebrafish 17beta-HSD 2 from ovarian tissue and found high expression also in the testis of adult fish and throughout embryogenesis. The enzyme, though, is inactive likely due to a non-sense N-terminal region including a dysfunctional cofactor binding motif. Replacement of the affected part by the corresponding human 17beta-HSD 2 sequence fully restored enzymatic activity. Comparison of all retrieved 17beta-HSD 2 sequences indicates that this functional loss may have occurred only in zebrafish, where steroid inactivation at position C17 seems to pursue without the protein studied. The closely related 11beta-HSD 2 is unlikely to substitute for 17beta-HSD 2 since in our hands it did not catalyze the respective oxidation of testosterone or estradiol.

17-Hydroxysteroid Dehydrogenases↗

PubMed2006

Bioinformatic identification and characterization of new members of short-chain dehydrogenase/reductase superfamily.

With about 60 genes known in the human genome, short-chain dehydrogenases/reductases (SDRs) form a large gene family with important implications for medicine. They are known to be involved in carcinogenesis (e.g. breast and prostate cancer) as well as in metabolic and degenerative defects such as the pathogenesis of Alzheimer's disease, osteoporosis and diabetes. Uncharacterized SDRs are thus potential candidates for many monogenic and multifactorial human diseases. The identification and functional analysis of such SDR enzymes is therefore the primary goal of the study leading to new targets for drug development. In all taxa (bacteria, plants, insects, vertebrates), members of SDR superfamily are known. Up to now, there are several thousand members annotated many of which have not been characterized biochemically with regard to enzymatic activity, substrate specificity, or subcellular localization. We bioinformatically identified 250 vertebrate candidate genes belonging to the SDR superfamily using the BioNetWorks software SDR finder. The number was reduced to 95 after continuative analysis, including manual SDR motif verification and focus on human, rat and murine enzymes. Here, we present several new mammalian SDRs that were clustered into several enzymatically different groups by detailed phylogenetic analyses. Furthermore, characteristic mRNA expression patterns were identified for some of these genes by a recently developed in silico Northern blot method supporting their putative functions in retinoid, steroid, sugar and other metabolic pathways.

Amino Acid Sequence↗

PubMed2006

In silico Northern blot, an automated method to determine expression patterns from EST databases, reveals tissue specificity of murine 17beta-hydroxysteroid dehydrogenase type 11.

In this study, we developed an automated in silico Northern blot (ISNB) for analysis of gene expression patterns from EST databases. This kind of analysis can facilitate initial enzyme characterization by providing tissue distribution patterns. For proof of principle, we analyzed the expression pattern of well-characterized murine 17beta-hydroxysteroid dehydrogenases type 1 and 4. Less characterized murine 17beta-hydroxysteroid dehydrogenase type 11 (Dhrs 8) also was included and processed bioinformatically (ISNB) and further analyzed by Northern blot. The 17beta-hydroxysteroid dehydrogenase type 11 showed the same wide expression pattern by in silico and by wet laboratory approaches. The data point to its involvement of the enzyme in lipid metabolism. The quality of the ISNB relies on the quality of EST-databases. However, our approach is an easy and versatile tool of potentially universal application.

17-Hydroxysteroid Dehydrogenases↗

PubMed2005

Interspecies comparison of gene structure and computational analysis of gene regulation of 17beta-hydroxysteroid dehydrogenase type 1.

17Beta-hydroxysteroid dehydrogenase type 1 (HSD17B1) is a key enzyme of 17beta-estradiol biosynthesis, and in rodents is additionally involved in testosterone biosynthesis. The human HSD17B1 gene, located on chromosome 17q12-21, is duplicated in tandem, with the 3'-copy being the functional gene. Here we show by sequencing the gene from a diverse set of related species that this duplication is of very recent evolutionary origin, having occurred in the common ancestor of Hominoidae (apes and humans) while being absent in the closely related Old World monkeys (Macaca) and the outgroup species Tupaia belangeri and Mus musculus. By computational analysis of the conserved regulatory elements in the 5'-untranslated (5'-UTR) and putative promoter region of the HSD17B1 gene and, where present, pseudogene, across our broad sample of species we can show significant differences that might point to the origin of the divergent substrate specificity of human and rodent HSD17B1 and highlight potential functionally relevant differences in regulatory patterns in different evolutionary lineages.

5' Untranslated Regions↗

PubMed2005

Inhibition of 17beta-hydroxysteroid dehydrogenases by phytoestrogens: comparison with other steroid metabolizing enzymes.

Effects of phytoestrogens on human health have been reported for decades. These include not only beneficial action in cancer prevention but also endocrine disruption in males. Since then many molecular mechanisms underlying these effects have been identified. Targets of phytoestrogens comprise steroid receptors, steroid metabolising enzymes, elements of signal transduction and apoptosis pathways, and even the DNA processing machinery. Understanding the specific versus pleiotropic effects of selected phytoestrogens will be crucial for their biomedical application. This review will concentrate on the influence of phytoestrogens on 17beta-hydroxysteroid dehydrogenases from a comparative perspective with other steroid metabolizing enzymes.

17-Hydroxysteroid Dehydrogenases↗

PubMed2005

Androgen metabolism via 17beta-hydroxysteroid dehydrogenase type 3 in mammalian and non-mammalian vertebrates: comparison of the human and the zebrafish enzyme.

Formation and inactivation of testosterone is performed by various members of the 17beta-hydroxysteroid dehydrogenase (17beta-HSD) family. The main player in testosterone formation is considered to be 17beta-HSD type 3, which catalyzes the reduction of androstenedione to testosterone with high efficiency and is almost exclusively expressed in testis. So far, only the mammalian homologs have been characterized but nothing is known about the role of 17beta-HSD type 3 in other vertebrates. In this study, we describe the identification and characterization of the zebrafish homolog. We found zebrafish 17beta-HSD type 3 to be expressed in embryogenesis from sphere to 84 h post-fertilization. Expression was also detected in various tissues of both male and female adults, but displayed sexual dimorphism. Interestingly, expression was not highest in male testis but in male liver. In female adults, strongest expression was observed in ovaries. At the subcellular level, both human and zebrafish 17beta-HSD type 3 localize to the endoplasmic reticulum. The zebrafish enzyme in vitro effectively catalyzed the conversion of androstenedione to testosterone by use of NADPH as cofactor. Among further tested androgens epiandrosterone and dehydroepiandrosterone were accepted as substrates and reduced at C-17 by the human and the zebrafish enzyme. Androsterone and androstanedione though, were only substrates of human 17beta-HSD type 3, not the zebrafish enzyme. Furthermore, we found that both enzymes can reduce 11-ketoandrostenedione as well as 11beta-hydroxyandrostenedione at C-17 to the respective testosterone forms. Our results suggest that 17beta-HSD type 3 might play slightly different roles in zebrafish compared with human although testosterone itself is likely to have similar functions in both organisms.

17-Hydroxysteroid Dehydrogenases↗

PubMed2004

The role of 17 beta-hydroxysteroid dehydrogenases.

The biological activity of steroid hormones is regulated at the pre-receptor level by several enzymes including 17 beta-hydroxysteroid dehydrogenases (17 beta -HSD). The latter are present in many microorganisms, invertebrates and vertebrates. Dysfunctions in human 17 beta-hydroxysteroid dehydrogenases result in disorders of biology of reproduction and neuronal diseases, the enzymes are also involved in the pathogenesis of various cancers. 17 beta-hydroxysteroid dehydrogenases reveal a remarkable multifunctionality being able to modulate concentrations not only of steroids but as well of fatty and bile acids. Current knowledge on genetics, biochemistry and medical implications is presented in this review.

17-Hydroxysteroid Dehydrogenases↗

PubMed2004

Identification and characterization of 17 beta-hydroxysteroid dehydrogenases in the zebrafish, Danio rerio.

The 17 beta-hydroxysteroid dehydrogenases (17 beta-HSDs) are key enzymes in the final steps of steroid hormone synthesis. 17beta-HSD type 1 (HSD17B1) catalyzes the reduction of estrone to estradiol, while type 3 (HSD17B3) performs the conversion of androstenedione to testosterone. Here we present a functional genomics study of putative candidates of these enzymes in the zebrafish. By an in silico screen of zebrafish EST databases we identified three candidate homologs for both HSD17B1 and HSD17B3. Phylogenetic analysis, unique expression patterns (RT-PCR) during embryogenesis and adulthood, as well as activity measurements revealed that one of the HSD17B1 candidates is the zebrafish homolog, while the other two are paralogous photoreceptor-associated retinol dehydrogenases. All three HSD17B3 candidate genes showed nearly identical, ubiquitous expressions in embryogenesis and adult tissues and were identified to be paralogs of HSD17B12 and a yet uncharacterized putative steroid dehydrogenase. Phylogenetic analysis shows that HSD17B3 and HSD17B12 are descendants from a common ancestor.

17-Hydroxysteroid Dehydrogenases↗

PubMed2003

Characterization of 17beta-hydroxysteroid dehydrogenase type 7 in reproductive tissues of the marmoset monkey.

In contrast to the known rodent enzymes, the physiological significance of 17beta-hydroxysteroid dehydrogenase type 7 (17HSD7) and its presumed function in reproductive biology is not well understood in primates. As a first step, we recently cloned the complete coding regions of human and marmoset monkey (Callithrix jacchus) 17HSD7 (cj17HSD7). In the present work the complete cDNA of marmoset 17HSD1 (cj17HSD1), including the proximal promoter region, and a partial sequence of marmoset aromatase (cjARO) were sequenced in order to compare the expression of these estradiol synthesizing enzymes with that of 17HSD7 in a primate model and to identify tissues where 17HSD7 might participate in the pathway of estradiol synthesis. The gene structures of cj17HSD1 and cj17HSD7 were determined and proved to be very similar to the human orthologues. Northern hybridization showed that cjARO mRNA seems to be coexpressed preferably with cj17HSD1 in placenta, whereas in other tissues it is expressed in parallel only with cj17HSD7. Especially in corpora lutea, the cj17HSD7 transcript is detectable throughout the luteal phase of the ovarian cycle and increases during pregnancy, in parallel with the transcript of aromatase. Results were confirmed by immunoblots and immunohistochemistry using new polyclonal antisera directed against cj17HSD7 and cjARO protein. The enzymatic conversion of estrone to estradiol was assessed in marmoset corpora lutea. The pattern of coexpression with aromatase supports the hypothesis that luteal 17HSD7 complements placental 17HSD1, ensuring continued estradiol synthesis throughout pregnancy in primates.

17-Hydroxysteroid Dehydrogenases↗

PubMed2002

Human 17beta-hydroxysteroid dehydrogenase type 5 is inhibited by dietary flavonoids.

Phytoestrogens contained in a vegetarian diet are supposed to have beneficial effects on the development and progression of a variety of endocrine-related cancers. We have tested the effect of a variety of dietary phytoestrogens, especially flavonoids, on the activity of human 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5), a key enzyme in the metabolism of estrogens and androgens. Our studies show that reductive and oxidative activity of the enzyme are inhibited by many compounds, especially zearalenone, coumestrol, quercetin and biochanin A. Among flavones, inhibitor potency is enhanced with increased degree of hydroxylation. The most effective inhibitors seem to bind to the hydrophilic cofactor binding pocket of the enzyme.

17-Hydroxysteroid Dehydrogenases↗

PubMed2002

Association studies between microsatellite markers within the gene encoding human 11beta-hydroxysteroid dehydrogenase type 1 and body mass index, waist to hip ratio, and glucocorticoid metabolism.

Two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) interconvert active cortisol (F) and inactive cortisone (E). 11beta-HSD1 is an oxo-reductase (E to F) expressed in several glucocorticoid target tissues, including liver and adipose tissue, where it facilitates glucocorticoid-induced gluconeogenesis and adipocyte differentiation, respectively. We have isolated a full-length HSD11B1 genomic clone; the gene is more than 30 kb in length, not 9 kb in length as previously reported, principally due to a large intron 4. Two polymorphic (CA)(n) repeats have been characterized within intron 4: a CA(19) repeat 2.7 kb 3' of exon 4 and a CA(15) repeat 3 kb 5' of exon 5. The microsatellites, CA(19) and CA(15), were PCR amplified using fluorescent primers and were genotyped on an ABI 377 DNA sequencer from DNA of 413 normal individuals enrolled in the MONICA study of cardiovascular risk factors and 557 Danish men (ADIGEN study), of whom 234 were obese [body mass index (BMI), >/=31 kg/m(2) ] at draft board examination and 323 were randomly selected controls from the draftee population with BMI below 31 kg/m(2) (mean +/- SE, 21.7 +/- 0.41). Genotypic data from the normal MONICA cohort was compared with gender, 5beta-tetrahydrocortisol+5alpha-tetrahydrocortisol/tetrahydrocortisone ratio, and waist to hip (W:H) ratio. When analyzed by allele length (0, 1, or 2 short alleles) for the CA(19) marker, there was a trend toward a higher 5beta-tetrahydrocortisol+5alpha-tetrahydrocortisol/tetrahydrocortisone ratio (P = 0.058) and an increased W:H ratio (2 vs. 0.1 short; P(c) = 0.10) with overrepresentation of short alleles. The opposite was true for the CA(15) locus, with longer alleles at this locus predicting increased 11beta-HSD1 activity, particularly in females. Genotypic data from the ADIGEN case-control population was compared with clinical markers of obesity such as BMI and W:H ratio. There was no significant difference in the distribution of either microsatellite marker between lean and obese groups. Allele distributions were binomial, as seen for the MONICA cohort, and the data were split accordingly (zero, one, or two short alleles). No significant association was seen between grouped alleles and the clinical parameters. No association was observed between HSD11B1 genotype and BMI in either population. These data suggest that 11beta-HSD1 is not a major factor in explaining genetic susceptibility to obesity per se. However, weak associations between HSD11B1 genotype, increased 11beta-HSD1 activity, and W:H ratio suggest that polymorphic variability at the HSD11B1 locus may influence susceptibility to central obesity through enhanced 11beta-HSD1 activity (E to F conversion) in visceral adipose tissue.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

PubMed2001

Gene structure and regulation of the murine epithelial calcium channels ECaC1 and 2.

The recently discovered epithelial calcium channels ECaC1 and ECaC2 are thought to play an important role in active calcium absorption in the intestine and kidney. Vitamin D-responsive elements (VDRE) were detected in the promoter sequence of human ECaC1 and regulation of ECaC by the steroid hormone 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) has been postulated. In this study we describe the structure of two murine ECaCs genes, each consisting of 15 exons localized on chromosome 6. Murine ECaC2 expression was found in many target tissues of 1,25-(OH)(2)D(3), including skin and osteoblastic cells, while ECaC1 expression is confined to the kidney. By screening the murine promoter sequences, we detected a putative VDRE in ECaC1 and an estrogen response element in ECaC2. However, experiments in mice with a mutant, nonfunctioning vitamin D receptor showed that expression of ECaC1 in the kidney and of ECaC2 in duodenum is regulated by calcium levels, but not by 1,25-(OH)(2)D(3). Also, estrogen-deficient ovariectomized (OVX) mice and OVX mice supplemented with estradiol showed unchanged duodenal ECaC2 expression compared with control mice. We conclude that ECaC expression in the kidney and the intestine is regulated by extracellular calcium but not by vitamin D or estrogen in vivo in mice.

Amino Acid Sequence↗

PubMed2001

17beta-hydroxysteroid dehydrogenase from the fungus Cochliobolus lunatus: structural and functional aspects.

17beta-Hydroxysteroid dehydrogenase (17beta-HSD) activity has been described in all filamentous fungi tested, but until now only one 17beta-HSD from Cochliobolus lunatus (17beta-HSDcl) was sequenced. We examined the evolutionary relationship among 17beta-HSDcl, fungal reductases, versicolorin reductase (Ver1), trihydroxynaphthalene reductase (THNR), and other homologous proteins. In the phylogenetic tree 17beta-HSDcl formed a separate branch with Ver1, while THNRs reside in another branch, indicating that 17beta-HSDcl could have similar function as Ver1. The structural relationship was investigated by comparing a model structure of 17beta-HSDcl to several known crystal structures of the short chain dehydrogenase/reductase (SDR) family. A similarity was observed to structures of bacterial 7alpha-HSD and plant tropinone reductase (TR). Additionally, substrate specificity revealed that among the substrates tested the 17beta-HSDcl preferentially catalyzed reductions of steroid substrates with a 3-keto group, Delta(4) or 5alpha, such as: 4-estrene-3,17-dione and 5alpha-androstane-3,17-dione.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

A guide to 17beta-hydroxysteroid dehydrogenases.

17beta-Hydroxysteroid dehydrogenases (17beta-HSD) are pivotal in controlling the biological potency of steroid hormones by catalyzing oxidation or reduction at position 17. Several 17beta-HSDs may as well metabolize further substrates including alcohols, bile acids, fatty acids and retinols. This review summarizes recent progress in the field of 17beta-HSD research provides an update of nomenclature.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

Molecular basis of D-bifunctional protein deficiency.

Peroxisomal disorders appear with a frequency of 1:5000 in newborns. They are caused either by peroxisomal assembly defects or by deficiencies of single peroxisomal enzymes. The phenotypes vary widely: affected humans may die very early in life within a few days to several months as a result of the impairment in essential peroxisomal functions as, for example, in Zellweger syndrome, or they may show only minor disabilities as is in acatalasemia. The deficiency of D-bifunctional protein, an enzyme involved in peroxisomal beta-oxidation of certain fatty acids and the synthesis of bile acids, causes a very severe, Zellweger-like phenotype. A number of different mutations in the gene coding for the enzyme were found in humans causing the total or partial loss of its enzymatic function. This paper gives a review of cases and their molecular basis.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

Evolution of 17beta-HSD type 4, a multifunctional protein of beta-oxidation.

17beta-Hydroxysteroid dehydrogenase type 4 (17beta-HSD4) is the most unusual among human 17beta-HSDs. It is characterized by a multidomain structure, in which the dehydrogenase domain is fused to a hydratase and a lipid transfer domain. 17beta-HSD4 not only inactivates estradiol by conversion to estrone but its three protein domains also participate in successive steps of peroxisomal beta-oxidation of long- and branched-chain fatty acids. We have compared the genomic structure of human 17beta-HSD4 and several homologous genes from lower animals and fungi. Our data suggest an evolutionary scenario for the three protein domains and indicate a highly dynamic history of the enzyme but also a very high conservation of multifunctionality. This suggests that the main function of human 17beta-HSD4 is still its involvement in fatty-acid metabolism, while steroid conversion is only a secondary and possibly minor activity in vivo.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

17beta-hydroxysteroid dehydrogenase type 7--an ancient 3-ketosteroid reductase of cholesterogenesis.

17beta-hydroxysteroid dehydrogenase type 7 (17beta-HSD7) is a novel estrogenic hydroxysteroid dehydrogenase from mammals. We modeled the three-dimensional structure of human 17beta-HSD7, analyzed the phylogeny of 17beta-HSD7 homologues and determined its expression pattern by in silico Northern blotting. Predominant expression is found not only in reproductive tissues (breast, ovary, placenta) but also in liver and developing brain, principal sites of cholesterol synthesis. The substrate binding pocket is opening towards a conserved membrane-associated helix, which is indicative for a conversion of a membrane component. 17beta-HSD7 shows significant homology to a yeast 3-ketosteroid reductase (ERG27) involved in ergosterol biosynthesis. Our results lead to the conclusion that 17beta-HSD7 is not only involved in estradiol production but plays another (and possibly more important) role as a 3-ketosteroid reductase in cholesterogenesis. This agrees with the striking absence of 17beta-HSD7 homologues in the complete genomes of Drosophila and C. elegans, which are both auxotrophic for cholesterol.

17-Hydroxysteroid Dehydrogenases↗

PubMed2001

Mechanisms of estradiol inactivation in primate endometrium.

In uterine endometrium, the level of estradiol is controlled by oxidative 17beta-hydroxysteroid dehydrogenase (17HSD) activity which converts the bioactive hormone to the less active compound estrone. At least three different types of 17HSD (types 2, 4 and 8) use estradiol as their preferred substrate and may contribute to the overall rate of estradiol-inactivation in the uterus. In this study the marmoset monkey (Callithrix jacchus) was used for the investigation of the particular contribution of each type of 17HSD. Northern Blots revealed essentially the same tissue distribution as in the human. Likewise, uterine 17HSD enzyme activity increases in the secretory phase of the reproductive cycle, in parallel to the rise in circulating progesterone levels. Northern analysis of uteri from defined time points of the reproductive cycle showed that only the level of 17HSD2 expression is strongly upregulated in the secretory phase, whereas 17HSD4 and 17HSD8 seem to be expressed constitutively.

17-Hydroxysteroid Dehydrogenases↗